Is it normal to randomly be really sad and miss someone?

I think about and miss him everyday but lately I've been doing okay handling it but some days out of nowhere I'll just randomly get super sad and sometimes even cry. Other days I feel like I can survive but days like today I just really miss him and then I start looking at pictures of him and miss him more... If all goes well I'll see him in about 4 months but that's too long 😥 I don't want to overwhelm him by trying to text him all the time either because we're not actually dating (long story) but I just miss him a lot... this can even randomly happen when I'm busy and not supposed to be thinking of him. I do love him but this is starting to become too much sometimes